1. Field of the Invention
The present invention relates to a switch, and more particular, to a thin-type switch mountable on a printed board.
2. Background Art
Conventionally, a thin-type switch mountable on a printed board comprises, for example, a housing having a space therein, a first stationary terminal having an end provided outside the housing and the other end provided inside the housing and provided with a contact portion having a contact groove, a second stationary terminal having an end provided outside the housing and the other end provided inside the housing and provided with a contact portion, a contact piece provided in the housing, provided at an end thereof with a stationary portion, which is latched in the contact groove of the first stationary terminal to contact with the contact portion of the first stationary terminal, and at the other end thereof with a moving portion capable of contacting with the contact portion of the second stationary terminal, the contact piece being biased by a coil spring formed at an intermediate portion thereof in a direction of twist and in a direction of compression, and an operating body provided at a base end thereof with a support portion, which is provided in the housing and defines a center of swinging, the remaining portion thereof being capable of swinging about the support portion as the center of swinging, and formed with a push surface, which abuts against the contact piece, the operating body swinging to enable pushing the contact piece in the direction of twist (see JP-A-2004-327115).
With the switch described above, however, the operating body 60 directly pushes the moving portion 50e being one end of the contact piece 50 made of a coil spring, and the contact portion 50g of the operating body slides on the contact portion 40c of the second stationary terminal while twisting the contact piece 50. Therefore, when the operating body 60, the contact piece 50, etc. involve dispersion in outside dimension and assembly accuracy, unexpected elastic deformation such as warping of the moving portion 50e, or the like is liable to occur. Consequently, dispersion is liable to generate in contact pressure, at which the contact portion 50g of the operating body contacts with the contact portion 40c, and so the operating characteristics are liable to become unstable. Accordingly, when it is tried to ensure a desired operating characteristics, the switch described above needs high part accuracy and assembly accuracy, so that manufacture is not easy.
Also, in order to perform contact switchover in the switch described above, it is necessary to increase a twist angle of the moving portion 50e. Therefore, there is caused a problem that a large operating force is necessary and a torsional moment acting on the contact piece 50 becomes large to make the switch susceptible to fatigue and short in life.